We have observed that photons (light) as well as electrons, pions, neutrons and protons all exhibit wave behavior. It may seem strange to think of electrons, pions, neutrons and protons as waves - even stranger to think of particles as having a wavelength.
Since in our experiments all of these particles behaved like waves we were even able to draw some conclusions about the wavelengths, namely:
In 1924 a French physicist Louis de Broglie defined the wavelength of a particle (such as an electron to be:
Where h is Planck's constant (h = 4.14 ´ 10-15 eV) and p is the particle's momentum.
We discussed momentum in Module A, it is the product of an objects mass and velocity.
For this course it is most useful to have a mathematical relationship between a particle's wavelength, energy and mass. We can rewrite de Broglie's wavelength equation in these terms by following the steps below:
Since the energy in the double slit experiments is all kinetic energy we can rearrange the equation to give:
Substituting back into de Broglie's wavelength gives: